RF is normally adjusted to modify availability (see http://thelastpickle.com/2011/06/13/Down-For-Me/)
> for example, if I have 4 nodes cluster in one data center, how can RF=2 vs > RF=4 affect read performance? If consistency level is ONE, looks reading does > not need to go to another hop to get data if RF=4, but it would do more work > on read repair in the background. Read Repair does not run at CL ONE. When RF == number of nodes, and you read at CL ONE you will always be reading locally. But with a low consistency. If you read with QUORUM when RF == number of nodes you will still get some performance benefit from the data being read locally. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 23/05/2012, at 9:34 AM, Daning Wang wrote: > Hello, > > What is the pros and cons to choose different number of replication factor in > term of performance? if space is not a concern. > > for example, if I have 4 nodes cluster in one data center, how can RF=2 vs > RF=4 affect read performance? If consistency level is ONE, looks reading does > not need to go to another hop to get data if RF=4, but it would do more work > on read repair in the background. > > Can you share some insights about this? > > Thanks in advance, > > Daning >
